Usefulness of end-tidal carbon dioxide as an indicator of dehydration in pediatric emergency departments: A retrospective observational study

Bias between capnometry and venous carbon dioxide during initial assessment of pediatric emergency department patients: A video-based study

Objective

The bias of capnometry (ETCO2) and venous carbon dioxide (vpCO2) among pediatric emergency department (PED) patients triaged to critical care areas is unknown. We aimed to explore correlations and bias between ETCO2 and vpCO2¸and identify predictors of bias.

Methods

This was an observational, video-based, retrospective study comparing ETCO2 and vpCO2. Pediatric patients with simultaneous ETCO2 and vpCO2 data were included. Our primary aim utilized linear regressions to determine correlations and Bland-Altman analysis to assess bias. Our secondary aim utilized multiple regression to identify clinical covariates contributing to bias. Covariates included age, respiratory rate, heart rate, mean arterial blood pressure, capnometry interface, PED diagnosis, and PED disposition.

Results

A total of 200 PED patients with ETCO2 and vpCO2 data were included. The median (interquartile range [IQR]) ETCO2, vpCO2, and ΔCO2 in mmHg were 38 (32, 46), 49 (41, 61), and 11 (4, 20), respectively. ETCO2 (r = 0.76) and ΔCO2 (r = 0.71) were highly correlated with vpCO2. The mean bias between ETCO2 and vpCO2 was -14.1 mmHg (95% confidence interval [CI], -41.9 -13.7). The bias between ETCO2 and vpCO2 increased at higher values of each measure. ETCO2 sampling interface was the only independent predictor of vpCO2 in our multivariate analysis. Patients requiring bag-valve mask (BVM) ventilation had the highest median bias between ETCO2 and vpCO2 (29 mmHg, IQR 15, 37).

Conclusion

ETCO2 and vpCO2 were highly correlated. However, bias increased at higher levels of both ETCO2 and vpCO2. Among PED patients, ETCO2's ability to approximate vpCO2 diminishes with worsening hypercarbic respiratory failure.

Can Non-Invasive Capnography and Integrated Pulmonary Index Contribute to Patient Monitoring in the Pediatric Emergency Department?

OBJECTIVES

Noninvasive capnography (NICG) devices can measure oxygen saturation, end-tidal carbon dioxide (EtCO2), respiratory rate, heart rate values and integrated pulmonary index (IPI). This study aimed to evaluate patients who were monitored using NICG for various indications in a pediatric emergency department and to determine its contribution to patient management in the pediatric emergency department (PED).

METHODS

In this study, children aged <18 years who had been monitored with a NICG at the PED in our university between August 2018-May 2019 were evaluated. Of them 48 patients' file records and monitored capnography parameters such as heart rate, respiratory rate, blood pressure, capillary refill time, Glasgow Coma Score, SpO2, EtCO2, IPI recorded in the forms were reviewed.

RESULTS

Patients most often presented to the emergency room due to seizures (35.4%), change in consciousness (22.9%), other neurological reasons (18.8%) with %50 were female. Seizure treatment(16.7%), circulatory-respiratory support(16.7%), and antiedema treatments(6.3%) were required for 39.5% patients as life-saving interventions, and 72.9% patients were hospitalized. Patients with low IPI(<8) values at the beginning and decreasing IPI (<8) measurements within monitoring period needed more life-saving treatments(p=0.005 and p=0.001, respectively). Low IPI values of the patients during monitoring showed a significant difference in the decision to be hospitalized(p=0.048).

CONCLUSIONS

The results of the present study indicate that monitoring with NICG in the pediatric emergency room can be an important early indicator in establishing clinical prediction. The study particularly points out that the IPI value can be a guide in decisions regarding life-saving treatment and hospitalization. Among the capnographic data of these patients who had a change in consciousness IPI values those measured at the beginning and within the monitorizarion period showed a significant correlation with low GCS (<8) (r=0.478, p=0.001 and r=0.456, p=0.02, respectively). Prospective comprehensive large scale studies are needed to examine the use of NICG and IPI in routine PED practice for various indications.

Use of noninvasive volume assessment methods to predict acute blood loss in spontaneously breathing volunteers

OBJECTIVE

The use of noninvasive volume assessment methods to predict acute blood loss in spontaneously breathing patients remains unclear. We aimed to investigate changes in the pleth variability index (PVI), vena cava collapsibility index (VCCI), end-tidal carbon dioxide (EtCO2), pulse pressure (PP), and mean arterial pressure (MAP) in spontaneously breathing volunteers after acute loss of 450 mL blood and passive leg raise (PLR).

METHODS

This prospective observational study enrolled healthy volunteers in the blood donation center of an academic hospital. We measured the PVI, EtCO2, VCCI, MAP, and PP before blood donation; at the 0th and 10th minute of blood donation; and after PLR. The primary outcome was the changes in PVI, EtCO2, VCCI, MAP, and PP.

RESULTS

We enrolled thirty volunteers. There were significant differences among the four obtained measurements of the PVI, EtCO2, and MAP (P<0.001, P<0.001, P<0.001, respectively). Compared to the predonation values, post-hoc analysis revealed an increase in the PVI at the 0th min postdonation (mean difference [MD], 5.4±5.9; 95% confidence interval [CI], -7.6 to -3.1; P<0.001); a decrease in the EtCO2 and MAP at the 0th and 10th minute postdonation, respectively (MD, 2.4±4.6; 95% CI, 0.019 to 4.84; P=0.008 and MD, 6.4±6.4; 95% CI, 3 to 9.7; P<0.001, respectively). Compared with EtCO2 at the 10th minute, the value increased after PLR (MD, 1.8±3.2; 95% CI, 0.074 to 4.44; P=0.006).

CONCLUSION

The PVI and EtCO2 could detect early hemodynamic changes after acute blood loss. However, it remains unclear whether they can determine volume status in spontaneously breathing patients.

Utilizing End-Tidal Carbon Dioxide to Diagnose Diabetic Ketoacidosis in Prehospital Patients with Hyperglycemia

Background:

Early identification of diabetic ketoacidosis (DKA) may improve clinical outcomes. Prior studies suggest exhaled end tidal carbon dioxide (ETCO2) provides a non-invasive, real-time method to screen for DKA in the emergency department (ED).

Methods:

This a retrospective cohort study among patients who activated Emergency Medical Services (EMS) during a one-year period. Initial out-of-hospital vital signs documented by EMS personnel, including ETCO2 and first recorded blood glucose level (BGL), as well as in-hospital records, including laboratory values and diagnosis, were collected. The main outcome was the association between ETCO2 and the diagnosis of DKA.

Results:

Of the 118 patients transported with hyperglycemia (defined by BGL >200), six (5%) were diagnosed with DKA. The mean level of ETCO2 in those without DKA was 35mmHg (95% CI, 33-38mmHg) compared to mean levels of 15mmHg (95% CI, 8-21mmHg) in those with DKA (P <.001). The Area Under the Receiver Operating Characteristics (ROC) Curve (AUC) for ETCO2 identifying DKA was 0.96 (95% CI, 0.92-1.00). The correlation coefficient between ETCO2 and serum bicarbonate (HCO3) was 0.436 (P <.001) and the correlation coefficient between ETCO2 and anion gap was -0.397 (P <.001).

Conclusion:

Among patients with hyperglycemia, prehospital levels of ETCO2 were significantly lower in patients with DKA compared to those without and were predictive of the diagnosis of DKA. Furthermore, out-of-hospital ETCO2 was significantly correlated with measures of metabolic acidosis.

Effects of spinal immobilization at 20° on end-tidal carbon dioxide

OBJECTIVE

The aim was to determine the effect on end-tidal carbon dioxide (ETCO₂) of spinal immobilization (SI) at a conventional 0° angle and to investigate the usefulness of immobilization at a 20° angle for preventing possible hypoventilation.

METHODS

The study included 80 healthy volunteers, randomly divided into two groups. Spinal backboards and cervical collars were applied in Group 1 using a 0° angle and in Group 2 using a 20° angle, with the head up. SI was continued for 1 h, and ETCO₂ values were measured at the 0th, 30th and 60th minute.

RESULTS

There were no significant differences between the groups in 0th and 30th minute ETCO₂. However, after 60th minute, results showed a statistically significant increase in ETCO₂ in Group 1 (35.5 mmHg [IQR 25-75:35-38]) compared to Group 2 (34 mmHg [IQR 25-75:33-36]) (p < 0.001). During SI, there was a statistically significant increase in ETCO₂ in Group 1 (35 mmHg [IQR 25-75:34-36], 35.5 mmHg [IQR 25-75:34-37] and 36 mmHg [IQR 25-75:35-38] respectively at the 0th, 30th and 60th minute after SI) (p < 0.001) and no change in Group 2. Also, we found statistically significant differences between ΔETCO₂ levels in Groups 1 and 2 at all 3 time intervals.

CONCLUSION

Conventional SI with an angle of 0° led to an increase in ETCO₂ while subjects immobilization at a 20° angle maintained their initial ETCO₂ values. Immobilization at 20° may prevent decompensation in patients who have thoracic trauma or lung diseases or those who are elderly, pregnant, or obese.

Predictive value of capnography for severity of acute gastroenteritis in the emergency department

OBJECTIVE

This study first aims to assess the utility of ETCO2 levels in evaluating the severity of dehydration in adult patients that present to the ED with acute gastroenteritis. AGE. Second, it intends to evaluate the correlation between ETCO2 and several metabolic parameters: creatinine, pH, bicarbonate (HCO3), and bases excessive (BE).

METHOD

This prospective study was conducted with AGE patients in the ED of a training and research hospital between June 2018 and April 2019 after approval of the local ethical-committee. The two groups were defined according to the severity of AGE: mild and non-mild groups. For both groups, ETCO2 levels were measured and recorded on admission of the patients.

RESULTS

87 patients were included in the analyses. The median of ETCO2 values was found as lower in non-mild group than mild group; 30 (25-35) & 39 (33-34), respectively (p < 0.001). In ROC analysis for distinguishing between the both groups, the AUC value was found to be 0.988 and the best cut-off level was found as 33.5 with 95% sensitivity and 93% specificity. In addition, strong negative correlation between ETCO2 and creatinine (p < 0.001, r: -0.771) were found.

CONCLUSION

ETCO2 levels decreased in the non-mild group of AGE patients; it could be useful to distinguish the mild group from the non-mild group. ETCO2 could be a reliable marker in predicting AKI in the management of AGE patients.

Venous Physiology Predicts Dehydration in the Pediatric Population

BACKGROUND

No standard dehydration monitor exists for children. This study attempts to determine the utility of Fast Fourier Transform (FFT) of a peripheral venous pressure (PVP) waveform to predict dehydration.

MATERIALS AND METHODS

PVP waveforms were collected from 18 patients. Groups were defined as resuscitated (serum chloride ≥ 100 mmol/L) and hypovolemic (serum chloride < 100 mmol/L). Data were collected on emergency department admission and after a 20 cc/kg fluid bolus. The MATLAB (MathWorks) software analyzed nonoverlapping 10-s window signals; 2.4 Hz (144 bps) was the most demonstrative frequency to compare the PVP signal power (mmHg).

RESULTS

Admission FFTs were compared between 10 (56%) resuscitated and 8 (44%) hypovolemic patients. The PVP signal power was higher in resuscitated patients (median 0.174 mmHg, IQR: 0.079-0.374 mmHg) than in hypovolemic patients (median 0.026 mmHg, IQR: 0.001-0.057 mmHg), (P < 0.001). Fourteen patients received a bolus regardless of laboratory values: 6 (43%) resuscitated and 8 (57%) hypovolemic. In resuscitated patients, the signal power did not change significantly after the fluid bolus (median 0.142 mmHg, IQR: 0.032-0.383 mmHg) (P = 0.019), whereas significantly increased signal power (median 0.0474 mmHg, IQR: 0.019-0.110 mmHg) was observed in the hypovolemic patients after a fluid bolus at 2.4 Hz (P < 0.001). The algorithm predicted dehydration for window-level analysis (sensitivity 97.95%, specificity 93.07%). The algorithm predicted dehydration for patient-level analysis (sensitivity 100%, specificity 100%).

CONCLUSIONS

FFT of PVP waveforms can predict dehydration in hypertrophic pyloric stenosis. Further work is needed to determine the utility of PVP analysis to guide fluid resuscitation status in other pediatric populations.

Applications of End-Tidal Carbon Dioxide (ETCO2) Monitoring in Emergency Department; a Narrative Review

Capnograph is an indispensable tool for monitoring metabolic and respiratory function. In this study, the aim was to review the applications of end-tidal carbon dioxide (ETCO2) monitoring in emergency department, multiple databases were comprehensively searched with combination of following keywords: "ETCO2", "emergency department monitoring", and "critical monitoring" in PubMed, Google Scholar, Scopus, Index Copernicus, EBSCO and Cochrane Database.